Bucking Bronco 8N, help?

[Anonymous-0]

While brush hogging the tractor started bucking like a bronco. If I put my right hand up in the air I could be in a rodeo. Tractor will start trying to throw me anytime I accelerate to the 3/4 position. If I throttle down she runs great. If I keep bucking, it will sputter out and die. Will start again easily. Here is what I know.#

1. The tractor starts and runs very strong up to the 3/4 throttle position. Pulled all the plugs and no fouling even though this beast burns oil.

#2. With fuel shut off pulled plug off carb and got 1 3/4 ounces of clear clean gas. Seems I remember getting more? Open valve and get a steady trickle , about the size of a skinny night crawler worm. Pulled elbow screen and it is clean. Tank has gas, vent is open , and glass bowl screen is clear. I removed carb. and opened up. Quick look shows float to be in good shape, needle and spring are moving up and down.

#3 Checked govenor by goosing and feeling for resistance. Appears OK. Removed govenor to check for debris per FO4, Appears clean. Is it suppose to rattle inside? Are those the bearings. Mine makes a rattling noise when I shake it?

What direction would you proceed toward. I have avoided electrical because the tractor runs so strong up to the 3/4 position. There are no runtime issues such as 1 min, 1 hour as seen with the condensor and coil? The only thing I'm certain of is that at 3/4 throttle, with or without the brushhog, the tractor starts surging like a bronco.

Should I pursue carb, govenor, or begin looking at electrical issues. What would you do next?

 

[Dan]

Sounds like it needs more gas. Turn the big adjusting screw about a half more turn out and see if this does not make top end performance improve. You might have a partial clog on your main jet.

As far as your governor - yes, it supposed to rattle. Those are the balls that fly out on the curved dish in relation to engine RPM.

Dan

 

[Anonymous-0]

Did you check the filter/screen on the top of shutoff valve in tank? You'll have to drain tank & remove the valve. HTH Rusty

 

[old]

Sounds like the carb is set to lean. Open the main jet a 1/2 turn at a time and see if that helps. If it doesn't then pull it out all the way and with the drain plug out spray carb cleaner into the main jet and see if it that helps By the way when you put the main jet adjuster back in be sure you get it in right or it will not screw in as it should and can bend it.
Hobby farm

 

[Peter, Covington, LA]

My Model T started doing the same thing this past week, and it was a spark coil misfiring. Essentially, the car was running on 3 cylinders, which made it a bucking bronco.

In the Model T hobby, we have a saying: 99 percent of carburetor problems are in the ignition system.

Maybe this will help you track your problem. I hope so,

 

[Anonymous-0]

to see if its a fuel problem, pull the choke out when its buckin, if that helps it any, then you have a fuel problem. RP

 

[A. Bohemian]

Sorry we can't narrow it down for you more. But over the internet...

Quote: "...Open valve and get a steady trickle , about the size of a skinny night crawler worm...."

I have no idea what size worms get to be in your part of the country, but you should see a steady STREAM about the diameter of the drain plug hole. Anything else is suspect.

In fact, it sounds like this may be your problem. Check the screen inside the tank as per Rusty.

I did read your comment that the sediment bowl is clean now, but if you have found rust particles in your sediment bowl in the past, you probably have rust in the tank, especially if the tractor is kept outdoors.

In that case cleaning the screen is a TEMPORARY solution, and the problem is going to get worse over time, especially if you continue to keep the tractor outdoors when not in use.

Quote: "In the Model T hobby, we have a saying: 99 percent of carburetor problems are in the ignition system."

Peter is right, a lot of times what is an apparent fuel starvation problem can be caused by spark issues. So, if after getting a good, steady flow of gas you still have the problem, do the spark check thing.

Quote: "...this beast burns oil...."

In that case, if the fuel flow is rectified and the spark looks good on all four, I would do what Dell calls the dreaded compression check.

Remember, bush hogging is usually not light work and it can be very hard on an engine, making a motor which has adequate compression to start and run well run roughly.

In fact, it was when I could no longer run a shredder that I noticed the compression problem in my Farmall Super C. It would start and run and do light work just fine, without missing.

 

[Anonymous-0]

Thanks all for the replies. I'll put the govenor back on and drain the tank and check tank screen. I should have done this last month when it was off for the clutch. The compression on this engine is about 90psi per cylinder. I realize that most of the time its electrical but it just dosen't make sense when the engine is running so well. If its electrical would the coil be the first suspect?

 

[Cole Creek]

My 2N did that same thing. It was baling twin wrapped around one of the blades keeping it from flying into position and out of balance. It's worth a look.